package com.chanyachting.emall.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;


/**
 * 描述：
 *
 * @author $author$
 * @version $Revision$
 */
public class PicCheckCode extends HttpServlet {

    /**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	public static final String CODE_IN_SESSION="getImg";
	
	private Font mFont     = new Font("Arial Black", Font.PLAIN, 15); //设置字体
    private int  lineWidth = 2; //干扰线的长度=1.414*lineWidth
    private int  width     = 60; //定义图形大小
    private int  height    = 20; //定义图形大小
    private int  count     = 200;

    /**
     * 描述：
     *
     * @param fc 描述：
     * @param bc 描述：
     *
     * @return 描述：
     */
    private Color getRandColor(int fc, int bc) { //取得给定范围随机颜色

        Random random = new Random();

        if (fc > 255) {

            fc = 255;
        }

        if (bc > 255) {

            bc = 255;
        }

        int r = fc + random.nextInt (bc - fc);
        int g = fc + random.nextInt (bc - fc);
        int b = fc + random.nextInt (bc - fc);
        
        return new Color(r, g, b);
    }

    //处理post
    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

        doGet (request, response);
    }

    /**
     * 描述：
     *
     * @param request 描述：
     * @param response 描述：
     *
     * @throws ServletException 描述：
     * @throws IOException 描述：
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

        //response.reset();
        //设置页面不缓存
        response.setHeader ("Pragma", "No-cache");
        response.setHeader ("Cache-Control", "no-cache");
        response.setDateHeader ("Expires", 0);
        response.setContentType ("image/gif");

        // 在内存中创建图象
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics2D g = (Graphics2D) image.getGraphics ();

        //生成随机类
        Random random = new Random();

        // 设定背景色
        g.setColor (getRandColor (200, 250)); //---1

        g.fillRect (0, 0, width, height);

        //设定字体
        g.setFont (mFont);

        //画边框
        g.setColor (getRandColor (0, 20)); //---2
        g.drawRect (0, 0, width - 1, height - 1);

        //随机产生干扰线，使图象中的认证码不易被其它程序探测到
        for (int i = 0; i < count; i++) {

            g.setColor (getRandColor (150, 200)); //---3

            int x  = random.nextInt (width - lineWidth - 1) + 1; //保证画在边框之内
            int y  = random.nextInt (height - lineWidth - 1) + 1;
            int xl = random.nextInt (lineWidth);
            int yl = random.nextInt (lineWidth);
            g.drawLine (x, y, x + xl, y + yl);
        }

        //取随机产生的认证码(4位数字)
        String sRand = "";

        for (int i = 0; i < 4; i++) {

            String rand = String.valueOf (random.nextInt (10));
            sRand += rand;

            // 将认证码显示到图象中,调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.setColor (new Color(20 + random.nextInt (130),
                    20 + random.nextInt (130), 20 + random.nextInt (130))); //--4--50-100

            g.drawString (rand, (13 * i) + 6, 16);

            
        }

        // 将认证码存入SESSION
        request.getSession ().setAttribute (CODE_IN_SESSION, sRand);

        // 图象生效
        g.dispose ();

        // 输出图象到页面
        ImageIO.write (image, "PNG", response.getOutputStream ());
    }
}
